Motors are used to drive the spin baskets and/or agitators of washing machines in order to wash clothing that is in the spin basket. There are many phases of the motor operation corresponding to different phases in the wash cycle. One part of the wash cycle is an agitate cycle whereby the agitator is oscillated backwards and forwards in order to agitate clothing in the spin basket.
The motor used to operate the agitator can be of the electronically commutated inside-out type permanent magnet rotor, or brushless DC motor. The stator of the motor is fixed to the underside of the bowl and/or is coupled to the agitator. The stator has a number of radially aligned poles extending outwardly from a hub. The poles each carry a winding, and every third winding is connected to form a total of three windings in the stator. The electronic commutator can energise the windings in turn, in order to rotate the rotor in the desired manner.
Traditionally, a two phase firing regime is used to energise the windings in an electronically commutated motor. In two phase firing, at any point in time two of the windings are energised, with the third winding remaining un-energised or floating. With two phase firing, the maximum torque capability of the motor decreases above a particular speed threshold. This can reduce effectiveness of the motor, and the effectiveness of washing, when used in a washing machine.